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Tiny fluid droplets trapped inside some of the world's oldest rocks could offer new clues about the way the earth formed and how life began. A new laser ablation inductively coupled plasma mass spectrometry (ICPMS) facility at the University of Leeds will allow researchers to analyse the fluid inclusions in quartz crystals, which harbour the secrets of oceans that existed aeons ago. Liquid water is thought to have been present on the earth more than 4 billion years ago but obtaining samples from such murky depths of time is impossible. However, rocks from around 3.8 billion years ago - the oldest on the planet could allow researchers to carry out analysis on ancient seawater trapped in tiny pockets within rock crystals. The Leeds scientists are investigating quartz formed in lava flows under the sea. This quartz has been unaffected by geological processes for billions of years. This ensures that the fluid inclusions, which are between one hundredth and one thousandth of a millimetre in diameter are just as they were when the quartz formed between 3.8 and 2.2 billion years ago. The new ICPMS facility, which was opened on April 25th, is the first of its kind in the UK. According to team member David Banks will allow the researchers to understand the chemistry of the sea when life began. "The sea was the birth place of life as we know it," he explains, "it is where the first biological molecules and microbes formed. It was a major factor in limiting the levels of oxygen in the earth's early atmosphere at concentrations much lower than we have today. Understanding its composition at the time the first life on Earth emerged will help us learn more about how the process began and how the first forms of life came about." Conventional methods of analysing fluid inclusions have relied on crushing small pieces of crystal to open the inclusions and dissolving the salts with water for analysis. This method requires thousands of inclusions to be present in the rock samples, and as Banks adds, the older methods can mix up different sea water of different ages. The scientists' new million pound laboratory, funded by JIF (Joint Infrastructure Fund) will allow them to use lasers to "drill" into individual fluid inclusions. The high temperature generated by the laser beam will vaporise the sea water within the inclusion and the vapour can then be analysed using mass spectrometry. The scientists involved in the project include Bruce Yardley, Robert Cliff, Andrew McCaig, Tom Shepherd and Banks. They are collaborating with Peter Appel of the Geological Survey of Denmark and Jens Gutzmer from the Rand Afrikaans University in Johannesburg. The researchers' aggregate expertise in fluid inclusions has been built up over at least the last decade and work with other techniques will ensure that the textural context of the measured inclusions can by properly characterised. Related links: |
 David Banks with the laser ablation ICPMS  The photo shows a laser drilling down through an emerald crystal. The pit has been coated with electrically conductive gold and the false colours indicate the depth of the pit. |
